Udk 619:579.62 Different Sensitivity of Various Serotypes of Listeria Monocytogenes to Lactic Acid Bacteria Bacteriocins

In this study the sensitivity of various serotypes of Listeria monocytogenes towards five lactic bacteria bacteriocins was investigated, at two incubation temperatures (37C for 24 h and 4C for 12 days); six serotypes were indentified in 50 clinical/human isolates of L. monocytogenes and eight among 48 isolates from foodstuffs. This microorganism was found in many foodstuffs in numerous studies during the last decade. Among the methods for typing Listeria, the greatest attention has been dedicated to serological typing, which defines the basic characteristics of Listeria antigens. Namely, it is well known that bactericideal or bacteriostatic effects of bacteriocins are not only expressed towardse closely related bacterial species, but also towards less closely related Gram positive bacteria, such as L. monocytogenes. Bacteriocins can be eventually added to food, with the aim of decreasing the risk of listeriosis to the minimum. It was discovered that the bacteriocins, originating from Lactococcus UW and Lactobacillus sake 148 did not express inhibitory effects on any Listeria serotypes, while those bacteriocins originating from Lactobacillus sake 265, Pediococcus 347 and Lactobacillus sake 706 had a listericidal effect towards almost every assessed serotype. The highest bactericid effect was expressed by bacteriocin towards serotypes 4c and 4, at 37C after 24h incubation and towards serotypes 1/2b and 4b after 12 days incubation at 4C. Thus, the incubation temperature and time influenced the inhibitory effects of bacteriocins.